EP-A-1075683 describes a foam control agent comprising (A) an organopolysiloxane material having at least one silicon-bonded substituent of the formula X-Ph, wherein X denotes a divalent aliphatic hydrocarbon group and Ph denotes an aromatic group, (B) a water-insoluble organic liquid, (C) an organosilicon resin and (D) a hydrophobic filler. The water-insoluble organic liquid (B) can for example be a mineral oil, liquid polyisobutene, isoparaffinic oil or vegetable oil. EP-A-1075684 describes a foam control agent of similar composition except that it does not contain water-insoluble organic liquid (B).
EP-A-578424 describes a foam control agent which contains an polydiorganosiloxane with alkyl side chains in which each alkyl side chain contains from 9 to 35 carbon atoms. The polydiorganosiloxane is used together with a finely divided hydrophobic particulate material, for example, hydrophobic silica, and optionally an MQ organosilicon resin. EP-A-1070526 describes such a foam control composition additionally comprising a stabilizing aid which is an organic compound having a melting point of from about 40 to 80° C., preferably a fatty acid, a fatty alcohol or an alkylphosphoric acid ester.
EP-A-210731 describes a particulate foam control agent comprising a silicone antifoam and an organic material having a melting point in the range 50-85° C. which comprises a monoester of glycerol and a 12-20C fatty acid, for example glyceryl monostearate, optionally in self-emulsifying form. The glyceryl monostearate is said not to affect the effectiveness of the silicone antifoam when it is released into the washing liquor. U.S. Pat. No. 5,238,596 describes a particulate foam control agent comprising a silicone antifoam and an organic material having a melting point in the range 45-85° C. which is a fatty acid, fatty alcohol or a monoester of glycerol and a 12-20C fatty acid, and a starch carrier.
GB-A-1523957 describes a foam control substance which comprises powdered or granular sodium tripolyphosphate, sodium sulphate or sodium perborate having on the surface thereof an organopolysiloxane antifoam agent which is at least partially enclosed within a mixture of a water insoluble wax having a melting point of 55-100° C. and a water insoluble emulsifying agent.
U.S. Pat. No. 4,609,490 describes a defoaming agent for bean curd manufacture which comprises not less than 90% glycerol fatty acid monoester with additives comprising a silicone which has defoaming activity and an inorganic substance such as calcium carbonate which has weak defoaming activity and can serve as a carrier.
EP-A-516109 describes a silicone defoamer comprising polydimethylsiloxane fluid, microparticulate silica, and polysiloxanes having vinyl and Si—H groups which are capable of reaction to form a crosslinked structure. The defoamer composition may contain a polyethylene glycol compound and a fatty acid ester compound to act as a surfactant.
There is still a need to provide more efficient foam control agents. We have now surprisingly found that if efficient foam control agents based on organopolysiloxane materials are combined with certain combinations of additives, an even more efficient foam control composition can be obtained.